Lecture 1

Question 1

Avian characteristics

Answer 1

• reflect flight requirements (but not all birds fly, and bats do)
• Feathers
• Skeleton-reduction and fusion (vertebral column, forelimbs, pectoral and pelvic girdle); pneumatic bones, fusion and elimination of bones, pneumatization of bones (but dneser), more genes associated with ossification than in mammals
• Furcula-fused clavicle
• Vertebral column- most posterior vertebrae fused together, pelvis expanded
• Ribs-
• Keeled sternum-not all
• Pygostyle-fused caudal vertebrae
• Wings-fusion and reduction
• Hindlimbs-Tibiotarsus and tarsus-metatarsus
• Skull-no teeth
• Large braincase (large eye sockets), brain structure- seat of learning
• Respiration-lungs and air sacs, 4 chm heart, oviparous
• Eggs-endothermy-no live births

Question 2

Shared avian and reptilian characteristics

Answer 2

• All are Diapsid-Sauropsid
• Single middle ear bone=columella
• Multiple bones in lower jaw
• Articulate/quadrate joint
• Single occipital condyle (mammals have 2)
• Large yolked egg

Question 3

Phylogenetic position

Answer 3

• Chordata-dorsal hollow nerve cord, notochord, postanal tail, pharyngeal gill slits
• Vertebrata/Craniata- vertebrae (or arcualia), canium + tripartite brain most closely related to eurchordata, plus genetic and developmental features.
• Amniotic Vertebrate-extraembryonic membranes, yolk, amniotic cavity, aminion, allantois, chorion, shell
• Diapsud (two temporal openings)- Sauropsid (lung structure)
• Archosauria- antorbital fenestra=hole in front of eyes
• Common ancestor with Archosaurs
• Theodont or theropod?-long rancorous debate

Question 4

Thomas H. Huxley

Answer 4

1860’s recognized similarities between Archaopteryx and theropod dinosaurs. Campsognathus- proposed theropod common ancestor-too little evidence

Question 5

Gerhard Heilman

Answer 5

1926- “The origin of Birds”-discounted similarities as convergence

Question 6

John Ostrom

Answer 6

1964-Too many similarities for convergence (wrist half moon shape, claw on hind foot)

Question 7

Allan Feduccia/Larry Martin

Answer 7

1980s-present: advocate theodont

Question 8

Current

Answer 8

Birds included in dinosaur clade

Question 9

What features determine that birds share a common ancestor with Dinosaurs

Answer 9

a. Dinosauria-hole in hip; bipedial
b. Dinosauria-Saurischian- pelvis with three radiating bones

(New phylogeny proposed)

Question 10

Chordata

Answer 10

pharyngeal gill slits, post-anal tail, dorsal hollow nerve cord, notochord

Question 11

Vertebrata/Craniata

Answer 11

• vertebrae (or arcualia), cranium/tripartite brain, closely related to euchordata, genetic and developmental features

Question 12

Amniotic vertebrate

Answer 12

-extraembryonic membrane, yolk, amniotic cavity, amnion, allantois, chorion, shell

Question 13

Diapsid

Answer 13

-two temporal openings

Question 14

Sauropsid

Answer 14

-Lung structurea

Question 15

Archosauria vertebrates

Answer 15

• anteorbital fenestra- hole in front of eye